Capstan construction



Aug. '18, 1970 M.-FURsT ETAI- CAPSTAN CONSTRUCTION original Filed Feb. 9, 1967 INVENTORS MARCEL FURST I MERVIN ll.. FALK RNEYS United States Patent Office U.S. Cl. 242-19 3 Claims SABSTRACT 0F THE DISCLOSURE Tape roll ldrive capstan having a periphery wherein the outer margins are harder than intermediate Iportions so as to eliminate cupping of tape rolls.

GROSS REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 614,967, filed Feb. 9, 1967, entitled Capstan Construction and Method of Manufacture, now Pat. No. 3,441,- 998.

BACKGROUND OF THE INVIENTION This invention relates to tape transport apparatus, and more particularly to a capstan construction of a type for driving supply and take-up rolls of tape to transfer a length of tape from the former to the latter.

In apparatus for feeding magnetic recording tape, a common problem which is frequently encountered is cupping of the rolls of tape. Briefly, this problem refers to the phenomenon whereby after tape has been fed between supply and take-up rolls a number of times, the rim or edge of the roll becomes somewhat concave as distinguished from the desired rectilinear configuration which it had upon being initially employed. Thus, where the edge of a roll has become concave, cupping exists and introduces deleterious effects to the tape itself as well as serving to introduce well-known problems with respect to the transducing of signals to and from the tape.

Accordingly, it is readily evident that apparatus for feeding tape from a supply to a take-up roll wherein cupping can be minimized or eliminated becomes highly desirable.

OBJECTS OF THE INVENTION It is a general object of the present invention to provide a capstan construction whereby in the feeding of tape from a supply to a take-up roll cupping of tape rolls is essentially eliminated.

Other objects of the invention will become readily apparent from the following detailed description of a preferred embodiment.

As used herein, the term edge driven refers to the edge of the rolls as distinguished from the edges of the tape. Another term for the present arrangement might be rim-driven rolls, but it is readily apparent that the rolls have no rim.

SUMMARY OF THE INVENTION Briefly stated, in the capstan construction disclosed herein, there is provided an annular rotating body adapted to be mounted for rotation. The periphery around the body is adapted to engage and press against the edge of a roll of tape so as to develop reactive forces in the periphery such that these reactive forces act radially outwardly thereof. The capstan construction herein is characterized by the fact that those reactive forces disposed 3,524,607 Patented Aug. 18, 1970 to oppose the longitudinal outer margins of the engaged roll of tape are at least as great as those reactive forces developed in between. According to the method of manufacture disclosed herein, a uniformly homogeneous material can be employed to form the periphery of the capstan.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partially in elevation cross-section showing a capstan construction according to the invention and schematically disposed in conjunction with supply and take-up rolls;

FIG. 2 is an enlarged detail view, in section, of a portion of the capstan construction shown in FIG. 1 prior to the attachment of llanges thereto;

FIG. 3 is an enlarged detail view, in section, similar to FIG. 2 after attachment of flanges thereto;

FIG. 4 is a further enlarged detail view, in section, of that portion of FIG. 3 taken along the lines 4 4 thereof;

FIGS. 5 and 6 respectively show rolls of tape with and without the problem of cupping; and

FIG. 7 is a diagram of the invention showing a detailed portion of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT There has been provided herein a capstan construction of a type for edge-driving supply and take-up rolls of tape for transferring a length of tape from the former to the latter. Thus, the edges of the rolls are engaged by the capstan periphery. The cylindrical capstan periphery includes a resilient driving surface bounded at the cylindrical end edges to preclude expansion laterally of the driving surface. The back side of the resilient driving surface is supported by a homogeneous body as provided, for example, by a -metal hub.

Thus, the capstan construction generally comprises a rigid annular hub adapted to be mounted for rotation. A relatively thin layer of resilient material encircles the hub and is adapted for edge-driving engagement with rolls of tape. A pair of flanges are carried by the ends of the hub and extend radially outwardly across the end edges of the driving layer. The flanges serve to compress the ends of the layer so as to support the layer against any endwise expansion of the layer under applied compression experienced during an edge-driving transfer of tape.

More particularly, referring to the drawings, a supply roll 11 and take-up roll 12 are arranged whereby a caplstan assembly 13 can be rotated to transfer tape 14 from hub 16 to take-up roll 12.

Capstan assembly 13 comprises an annular, generally cylindrical, hub 17 of a rigid material, such as cast aluminum. Hub 17 includes a cylindrical periphery 18 having an axial extent essentially co-extensive with the width of tape 14. i

Periphery 18 carries a relatively thin layer 19 of resilient material, preferably polyurethane. The material of layer 19 should be virtually completely free of any bubbles or pockets of porosity whereby uniform density of the material and support of tape is assured.

In the process of manufacturing capstan assembly 13, layer 19 is applied to hub 17, preferably by molding to form a structure as shown in FIG. 2. Layer 19 is disposed and dimensioned to provide end edges 21, 22. The edges are then reduced down to a point where they overhang the ends 23, 24 of hub 17 only slightly. This is preferably accomplished by grinding edges 21, 22 until the plane of ends 23, 24 is reached. When the grinding tool is removed, the resilience of the material of layer 19 causes edges 21, 22 to spring back an amount suitable for providing the advantageous anti-cupping property to the capstan. The extent to which edges 21, 22 then extend beyond ends 23, 24 has been found, in the case of a quarter-inch 3 wide periphery 18, of polyurethane, to run on the order of 0.001 inch.

By securing flanges 27, 28 to the ends of hub 17, a bulge 2S is thus formed on the driving surface of layer 19 by the axial compression of the ilanges acting on the overhanging portion 26 of layer 19. This step of axially compressing the overhanging portion 26, therefore, serves to form bulge 25. Thereafter, flanges 27, 28 are coupled, as by screws, to the respective ends 23, 24 of hub 17.

Thus, the bounding surface of a side Wall member, such as anges 27, 28 bears against each of the end edges 21, 22 of layer 19 and compresses them in a direction axially of hub 17 so as to form bulge 25 along the edge margins of layer 19.

A capstan construction, as described above, is adapted to be driven by a spindle 29 and mounted for rotation in edge-driving relation to supply and take-up rolls 11, 12.

In a particularly preferred embodiment, supply and takeup rolls 11, 12 may be resiliently urged, as by springs 31, 32 toward capstan 13. In this manner compression is applied to the face of layer 19.

A particularly preferred construction of the above arrangement has been built and successfully operated to eliminate cupping (as shown in FIG. for a onequarter inch Width of magnetic recording tape wherein the thickness of layer 19 ran on the order of 0.0625 to 0.125 inch. It Was found that the former dimension may be somewhat too thin to successfully accommodate splices in the tape and run-out found in the roll of tape and therefore represents a minimum thickness.

It has been observed (FIG. 7) that the reactive forces F1 must be at least as great as forces F2 to overcome the cupping problem completely. Whereas a thickness on the above order represents something of a minimum, there appears to be no particular maximum so long as the reactive forces along the outer margins 36, 37 equal or exceed forces F2.

The material of layer 19 preferably, as noted above, consists essentially of polyurethane and preferably has a hardness within a range on the order of 40-60 durometer (Shore A). Using xed anges as shown in the drawings, the tape edges of rolls 11, 12 preferably provide a closely spaced iit with the bounding surfaces 33, 34 of flanges 27, 28. Thus, a slight positive spacing between surfaces 33, 34 preferably runs on the order of 0.001 to 0.002 inch relative to the width of tape 14. Accordingly, the axial extent of periphery 18 is substantially coextensive with the width of tape 14.

Whereas in the foregoing preferred embodiment the construction entails a capstan of a type for drivably moving the edge of a roll of tape, it is to be understood that the term fcapstan construction of a type for edge driving as used herein and as appearing in the claims shall be deemed to include other annular rotating bodies of a type, for example, such as idler rolls and tape roll followers ,pr other arcuate tape guides such as employed, for example, in the spooling of tape or otherwise.

What is claimed is:

1. A capstan Construction of a type for edge-driving supply and take-up rolls of tape to transfer a length of tape from the former to the latter, said construction comprising an annular hub adapted to be mounted for rotation, a layer of resilient material encircling the hub and adapted for edge-driving engagement with rolls of tape, a pair of flanges carried by the ends of the hub and extending radially outwardly across the end edges of said layer, said flanges serving normally to compress the ends of said layer and further to support same against endwise expansion of the layer when under compression applied during said edge-driving engagement.

2. In a capstan construction of a type for engaging the edge of a. roll of tape, said construction having an annular rotating Ibody adapted to be mounted for rotation, and a periphery around said body adapted to engage and press against the edge of a roll to develop reactive forces in said periphery acting radially outwardly thereof, said periphery acting radially outwardly thereof, said periphery when so engaged being characterized by those of said reactive forces disposed in that portion of said periphery opposing the longitudinal margins of the engaged tape being greater than those of said reactive forces disposed laterally therebetween.

3. A capstan construction as dened in claim 2 wherein the material of said periphery is uniformly homogeneous.

References Cited UNITED STATES PATENTS 2,624,574 1/1953 Camras 226-183 X 2,657,871 1l/1953 Pettus 242-55.14 3,330,461 7/1967 Brand et al. 226-193 3,370,804 2/ 1968 Peyton 242-5512 GEORGE F. MAUTZ, Primary Examiner U.S. Cl. X.R. 226-191 

